The present invention relates to a series of novel diphenylpropylamino-pyridine compounds which are analogs of phenpyramine and endowed with spasmolytic and miorelaxing activity affecting the smooth muscular system, as well as with local anesthetic activity.
More particularly the present invention relates to a series of novel drugs having the structural general formula: ##STR2## in which the diphenylpropylamine group is bound to the position 2, 3 or 4 of pyridine ring; R can be hydrogen or a low linear or branched chain alkyl group having 1 to 4 carbon atoms or an arylalkyl group such as for instance the benzyl group; X can be a halogen selected from the group consisting of Cl, Br and I; Y is hydrogen or a halogen such as fluorine, bromine and chlorine or also a methoxy group; Z is O or H.sub.2 ; and n can be zero or 1, with the proviso that Z is H.sub.2 when n is 1.
Among the compounds comprised in the above general formula, that one in which Y.dbd.H, Z.dbd.H.sub.2, n.dbd.zero and NH is bound in position 4, currently named fenpyramine, is known from specialized literature.
The novel compounds according to the present invention can be prepared by the original preparation process of fenpyramine as described in U.S. patent application No. 111,468 filed on Jan. 11, 1980 (now abandoned) in the name of same applicants, which is herein incorporated by reference.
It is known that those drugs wich are endowed to a larger or lesser extent with a spasmolytic activity are mainly formed by the so-called neurotrope drugs, since their action comes out at the synthetic or gangliar level of afferent autonomic nervous system, so that the spasmolytic action is generally part of a set of collateral actions affecting various body organs and districts. Thus for instance the atropinic drugs making up the best known spasmolityc agents of natural origin have side effects both on the autonomic nervous system thereby affecting organs having a parasympathetic innervation (heart, eyes, exocrine glands), and on central nervous system with a global action which is not always foreseable and sometimes paradoxical. The non-desired activity of atropinic drugs is regarded to be due to an antagonistic selective action on muscarinic receptors, which is on the other hand necessary to the accomplishment of the spasmolytic activity.
It is therefore obvious that the variety of non-desired side effects owned by these alkaloids is a drawback when their spasmolytic action has to be therapeutically exploited.
On the other hand papaverine, which is the base element of papaverinic drugs, also named miotropic spasmolytic drugs as they act directly on the smooth muscular system, unlike the antimuscarinic ones whose action comes out through the cholinergic system, notwithstanding its effectiveness on animals has lost its importance in human therapy, because the relevant therapeutical doses do not have often a functional margin with respect to doses which are regarded as toxic.
In other words, the ideal spasmolytic drug should be endowed with a selective action on hollow smooth-muscled organs and not have side effects extending to other sites. A local anesthetic activity owned by this drug would further improve its therapeutical efficaciousness.